Orthodontic diagnostic equipment includes everything that must be taken by the orthodontist before the start of treatment to assess a case, make a proper diagnosis, set treatment goals and develop a treatment plan. This may include, but is not limited to:

models of dentition and occlusion studies (plaster models taken using fingerprints or a 3D digital scan)

a clinical examination, a medical, dental and orthodontic questionnaire,

intra and extraoral photographs,

reports from other dental or medical specialties that may be consulted depending on the nature of the patient's problems (periodontics, maxillofacial surgery, other dental or medical specialists),

X-rays depending on the case (panoramic, cephalometric, cone-beam volume computed tomography (CVCT))

imaging or various tests (MRI, scintigraphy, cardiorespiratory sleep computer (PCRS), etc.).

Dental X-rays

X-rays are essential for establishing a good diagnosis and identifying several problems that can not be "visualized" otherwise.

This section shows various radiographs that have been routinely taken to evaluate the rash and development of teeth in growing patients and have identified several other problems.

Extra teeth radiography orthodontic

(A) A routine panoramic X-ray seems to show a supernumerary tooth (red arrow). Another supernumerary tooth is present but has escaped our initial examination (yellow arrow). It was discovered only when an additional occlusal X-ray was taken to confirm the presence of the first supernumerary tooth. (B) 2 supernumerary teeth revealed by taking an occlusal X-ray. (C) At the visual examination of the dentition, nothing could suggest that such teeth were present in the palate! The patient was referred to the dentist for evaluation and extraction of supernumerary teeth.

Pathology detected during a routine examination in a 14 year old girl. The eruption of the second lower right molar (*) is blocked by a cystic lesion (arrows). Compare with the other side that is normal. The patient was referred to her dentist for further evaluation and treatment.

Pathology found on a routine radiograph. Around the left lower premolar area in a 7.8-year-old boy The patient was referred to his dentist for evaluation and treatment. More than 2.5 years later (10.4 years), after this intervention, everything is back to normal and the teeth continue their development and normal eruption. A single clinical examination in the mouth did not detect this lesion.

In orthodontics, the dental X-ray that we use most frequently is the panoramic shot that offers a good "overview" of the dentition and jaws and provides essential information for screening and diagnosis of several conditions and problems that may be found in infancy.

Comparison between different types of dental x-rays used in orthodontics.

Comparison between inter-proximal or re-coronary radiography (bitewings) (A) and panoramic radiograph (B) for the same 8-year-old boy. Both types of radiographs have their usefulness but give us different information that is complementary to each other. See legend below.

In comparing x-rays above, it is difficult to assess all jaw dentition with retrocoronary X-rays. These have traditionally had better resolution (more visible detail) than panoramic radiography but do not provide an overview that is also useful for assessing the presence or absence of teeth, their direction of eruption, space available and several anatomical structures described below. However, the new Digital Panoramic X-rays, like the ones we are now taking, provide as good and even better resolution and clarity as the retrocoronaries taken with traditional standard "films" while reducing the amount of irradiation. for patients.

Did you know that the amount of irradiation (X-rays) required for taking the two above-the-retrocoronic images (films) (A) is the same as that for taking the panoramic X-ray (B) using a film much bigger and covers a larger area? The new digital X-ray machines are even more efficient and use even less radiation to obtain better information.

➡ Learn more about irradiation from dental x-rays.

The denser and mineralized the tissue, the more it will appear "white" or gray on X-rays. The darker or darker the area is, the softer the tissues (gum, tongue, skin, etc.) or absent ("empty" spaces like the inside of the mouth, sinuses, etc.).

This x-ray is the orthodontic standard and is taken for all patients who are followed during the development of the dentition or who are undergoing treatment.

It is recommended to take a panoramic X-ray around the age of 8-9 in order to have a good overview of present and developing dentition.

It allows to evaluate:

the direction of eruption of the teeth;

the number of teeth (there may be missing or missing teeth);

their shape, size and degree of training (dental age - delay or advance);

the presence of pathologies (cysts, hypercalcification, resorption, wear, etc.).

It acts as a "crystal ball" in predicting eruption and tooth development during growth and development.

X-rays are a crystal ball predicting the future of dental eruption.

The panoramic radiography also show:

Temporomandibular joints (TMJ), which are the joints of the jaws (see illustration above),

The nasal cavity (CN) right and left and the nasal septum (septum) located in the middle. Obstructions and deviations can sometimes be detected on a panoramic X-ray.

The maxillary sinuses (sinuses), which are a cavity in the bone of the upper jaw. These regions look dark because they are "empty".

Several developing permanent teeth (buds) indicated by reds. Compare with the only 2 permanent teeth visible on periapical radiographs (A). It is thus possible to confirm the presence of all the teeth present and in formation, even if their eruption will not be done before 4-5 years for some of them.

The teeth in the mouth but also those in training. We can evaluate if there are missing teeth (anodontia), if there are excess teeth (supernumerary), their direction of eruption, the space available for the eruption. Based on the degree of permanent non-erupted tooth formation, it is possible to evaluate when these teeth should come out.

The lower alveolar nerve (green lines) passes through the jawbone and innervates the lower dentition.

The buds of the wisdom teeth (* blue) that are forming in each "corner" of the mouth. Even at age 8, we can tell this boy that he has 4 wisdom teeth that are forming. To predict if these third molars can come out properly is another thing however! To learn more about wisdom teeth.

Frequency of X-rays

The panoramic X-ray is taken at the beginning of treatment, towards mid-treatment to check the position of the teeth, the inclination of the roots and the presence of root wear (resorption), etc. and at the end of the treatment. It is also taken after the end of treatment at an interval of a few years to follow the evolution of wisdom teeth. During the mixed dentition phase (~ 6 to 12 years) it allows the orthodontist to detect the presence of eruption problems and other abnormalities and allows him to make recommendations that can minimize certain problems. It is an indispensable tool for orthodontic prevention and interception.

A cephalometric X-ray is taken at the beginning and at the end of the treatment. In some cases it can also be taken during treatment to check the inclination or protrusion of the anterior teeth. It is essential in the decision to extract teeth during the course to decrease a bimaxillary protrusion.

We adhere to the philosophy of reducing the radiation dose of patients by applying the principle known as the ALARA (As Low As Reasonably Achievable) dose for taking X-rays. Thus, we try to take as few X-rays as possible and as little as possible while allowing us to obtain the diagnostic information necessary for the treatment and follow-up of patients. Each radiological examination is based on our judgment and prior clinical examination. Whenever possible, we try to get some recent x-rays from your general dentist or other dental specialists that may be useful to us in order to avoid taking them back.

Surprising as it may seem, the radiation dose associated with the two small retro-coronary X-rays above (A) is exactly the same as that associated with the much larger panoramic radiograph (B), ie 10 μSv. Such a dose is considered very low.

➡ Learn more about irradiation from dental x-rays.

Radiological principle ALARA applied in orthodontics

Cephalometric radiographs

There are 2 types of cephalometric radiographs that we commonly use in orthodontics. Lateral and anteroposterior radiograph.

The side view is a side view of the face and skull. This X-ray is part of standard diagnostic equipment for all cases wishing to undertake major orthodontic corrections (complete treatment). It allows to evaluate:

the position of the jaws, their dimensions, their inclination with respect to each other,

which jaw is "deficient" in length in cases of large deviations,

the presence of vertical asymmetry between the 2 sides of the mandible,

the inclination of the anterior teeth, their protrusion, the horizontal distance between them and the vertical overhang,

The growth potential remaining; the skeletal maturity of the patient by evaluating the degree of formation of cervical vertebrae that are visible on this shot. This helps to determine residual growth and can help in the planning of orthodontic treatment.

the thickness and amount of alveolar bone surrounding and supporting the lower and upper anterior teeth,

the tonsils and vegetations, the upper respiratory tract, all of which are visible on this x-ray,

the presence and position of included teeth when present (including wisdom teeth),

temporomandibular joints; this X-ray gives only very limited information about these structures.

Sophisticated software makes it possible to measure a variety of variables on these x-rays and compare them with standards for similar groups in age, gender, etc. Simulations of growth and development as well as treatment modalities can also be performed. To see an example of simulation.

Lateral cephalometric X-rays can be used to assess the patient's profile, dentition, and jaws, and to correlate with facial photographs, allowing better planning of the treatment.

Cephalometric X-rays also assess the growth and development of jaws and orofacial structures by superimposing them during years of growth. Although, for the majority of cases, we only took this x-ray at the beginning and at the end of the treatment, these centers of growth studies * have databases with a multitude of X-rays and can show the changes X-ray that occur during growth. For example, the example shown in the AAOF Craniofacial Growth Legacy Collection ** shows changes occurring over 12 years of growth.

Orthodonctics Univ. Michigan growth center

The anteroposterior or "front-back" view is used to evaluate the skeletal structures of the jaws and skull in the dimension of width and height. We can detect the presence of asymmetries, deviations and other anomalies. It also allows evaluation of the nasal cavity and some less visible structures on other radiographs.

This radiograph is not taken routinely, but is especially so when we suspect the presence of asymmetries to confirm these doubts.

The advent of new "3D" X-rays (cone beam computed tomography (CVCT)) makes these X-rays much less necessary if not unnecessary.

The location of an included tooth and its "degree" of inclusion are critical in assessing the odds of success of housing that tooth in the dental arch.

Imaging is the best way to evaluate the position of an included tooth. The traditional X-rays described above are of great help for this purpose (see the examples on this page), but the new three-dimensional computed tomography (CBCT) not their equal to precisely locate a tooth and evaluate its environment.

Since 2012, we have been using the most efficient X-ray machine to obtain such images. Taking a single volume X-ray allows specialized software to obtain and extract hundreds of images in all dimensions, precisely locate a tooth, and assess whether adjacent structures (root other teeth, nerves and bones) are intact.

Using a cone-beam computed tomography to locate an included canine

Example of images obtained using a three-dimensional volume computed tomography to locate an included palatal canine (indicated by the arrows). This ensures that the root of the lateral is not affected by the included tooth.

Learn more about radiography and 3D digital imaging.

X-rays and pregnant patients

There is no medical contraindication to taking dental x-rays in a pregnant patient. Non-urgent procedures can however be postponed after pregnancy, at the request of the patient.

(Reference: Canadian Dental Association, February 2015)

Study models and intra-oral scans

Study models and photographs offer the best representation of a dentition and are essential in the planning of orthodontic treatments.

Study models and photographs offer the best representation of a dentition and are essential in the planning of orthodontic treatments.

Example of an intraoral scan of the dentition that can replace orthodontic study models.

The new intraoral digital scans allow to visualize in 3D the dentition and the occlusion of a patient and can replace the models of study.